State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
State Key Laboratory of Heavy Oil Processing, State Key Laboratory of Petroleum Pollution Control, China University of Petroleum-Beijing, Beijing 102249, China.
Water Res. 2022 Sep 1;223:119013. doi: 10.1016/j.watres.2022.119013. Epub 2022 Aug 22.
Peracetic acid (PAA)-based advanced oxidation processes (AOPs) were increasingly identified as the alternative scheme in wastewater treatment. Cost-effective and easily available catalyst for activation of PAA was in urgent demand for promoting engineering application process. In this study, a new type of biochar catalyst derived from pyrolysis of mixture of primary sludge (PSD) and secondary sludge (SSD) was prepared and showed effective PAA activation ability. The degradation of p-chlorophenol (4-CP) improved with PAA activation by mixed sludge derived biochar (PS-SDBC) than secondary sludge derived biochar (S-SDBC) and primary sludge derived biochar (P-SDBC), and the highest removal efficiency achieved by PS-SDBC with the PSD/SSD ratio of 5/5 (k=0.057 1/(M·min), pH 9). Correlation analysis firstly indicated that persistent free radicals (PFRs) rather than chemical composition and material structure dominated PAA activation and organic radicals (RO•) was proved to be the major reactive species through electron paramagnetic resonance (EPR) detection. The mixture of PSD and SSD caused the synergy of inorganic metals and organic matters through pyrolysis processes, resulting in larger specific surface area (SSA) (110.71 m/g), more abundant electron-donating groups (e.g., C = O, -OH) and massive defects (I/I = 1.519) of PS-SDBC than P-SDBC and S-SDBC, which eventually promoted PFRs formation. A fascinating phenomenon was observed in PS-SDBC/PAA system that the active sites of PFRs could be regenerated by RO• attacking onto PS-SDBC, which contributed to the wide pH applicability and continuous stability of PS-SDBC/PAA system in practical wastewater treatment. This study not only significantly deepened the understanding of the reaction mechanism between PAA and biochar, but also provided a potential PAA-based AOPs for micropollutants removal in wastewater.
过氧乙酸（PAA）基高级氧化工艺（AOPs）作为一种替代方案，在废水处理中得到了越来越多的关注。开发具有成本效益和易于获得的催化剂来激活过氧乙酸，对于促进工程应用过程至关重要。本研究采用热解混合初沉污泥（PSD）和二沉污泥（SSD）制备了一种新型生物炭催化剂，并展示了其有效激活过氧乙酸的能力。与二沉污泥衍生生物炭（S-SDBC）和初沉污泥衍生生物炭（P-SDBC）相比，混合污泥衍生生物炭（PS-SDBC）可显著提高过氧乙酸对 4-氯苯酚（4-CP）的降解效率，且当 PSD/SSD 为 5/5 时，PS-SDBC 的去除效率最高（k=0.057 1/（M·min），pH 9）。相关性分析首次表明，持久性自由基（PFRs）而非化学组成和材料结构主导着过氧乙酸的激活，并且通过电子顺磁共振（EPR）检测证明了有机自由基（RO•）是主要的反应性物质。PSD 和 SSD 的混合物通过热解过程产生了无机金属和有机物的协同作用，导致 PS-SDBC 具有更大的比表面积（SSA）（110.71 m/g）、更多的供电子基团（如 C=O、-OH）和大量缺陷（I/I=1.519），这最终促进了 PFRs 的形成。在 PS-SDBC/PAA 体系中观察到了一个有趣的现象，即 RO•攻击 PS-SDBC 可使 PFRs 的活性位点再生，这有助于 PS-SDBC/PAA 体系在实际废水处理中具有较宽的 pH 适用性和连续稳定性。本研究不仅显著深化了对过氧乙酸与生物炭之间反应机制的认识，而且为基于过氧乙酸的高级氧化工艺去除废水中的微量污染物提供了一种潜在的方法。
